1. Field of the Invention
The present invention relates to a bag transfer device used in bag filling and packaging apparatuses and the like and more particularly to a bag transfer device that includes a plurality of pairs of left and right grippers installed on a table rotating horizontally and a spacing adjustment mechanism provided for adjusting the spacing between the left and right grippers.
2. Description of the Related Art
Japanese Utility Model Application Publication No. H5-28169 discloses a bag transfer device that is installed in a bag filling and packaging apparatuses. This bag transfer device comprises an intermittently rotating table and a plurality of pairs of left and right grippers disposed at a constant angular spacing around the table. The left and right grippers are moved intermittently around a circular movement path when the table rotates. Each gripper has an arm and a clamping component installed at the distal end of the arm. The arms of the left and right grippers are axially supported respectively at their base portions by the table, and they are able to pivot in linear symmetry to each other within a horizontal plane.
The above-described bag transfer device includes, as a spacing adjustment mechanism for adjusting the spacing between the left and right grippers, a cylindrical cam, which is installed under the table so as to be able to move up and down, and an L-shaped lever, and it further includes a star cam and a latching pin. The center axis of the cylindrical cam coincides with the rotational axis of the table, and its upper end is the cam face. The L-shaped lever is axially supported by the table and is able to pivot in a vertical plane; and it has at one end a cam follower that rotates over the cam face of the cylindrical cam and also has at another end a press roller that comes into contact with the tail end of the arm and causes the arm to pivot. The star cam is rotated coaxially with the table. Also, the star cam can be rotated relative to the table and further can be positioned at a position after it has been rotated by a suitable angle. The latching pin is fixed to the arm.
In the above-described bag transfer device, while the table intermittently is rotating, the cam follower rotates over the cam face and moves up and down according to the shape (protrusion) of the cam face, which is accompanied by the opening and closing motions of the arms of the left and right grippers, so that the spacing between the left and right grippers (and especially the spacing between the clamping components) increases or decreases within a specific range. When the spacing between the left and right grippers decreases to a specific value, the latching pin comes into contact with the star cam. The maximum spacing of the left and right grippers is determined by the maximum height of the cam face of the cylindrical cam, and the minimum spacing of the left and right grippers is restricted by the star cam.
When the bag size (and particularly the bag width) is changed (or bags of different sizes are processed by bag transfer device), the maximum and minimum spacing of the left and right grippers has to be adjusted to match the width of the changed (or different) bag. This can be done by raising or lowering the cylindrical cam and rotating the star cam relative to the table.
Japanese Patent Application Laid-Open (Kokai) No. H9-95318 is similar to Japanese Utility Model Application Publication No. H5-28169, and it discloses also a bag transfer device. This bag transfer device includes an intermittently rotating table and a plurality of pairs of left and right grippers disposed at a constant angular spacing around the table. In this bag transfer device, instead of the cylindrical cam and star cam of Japanese Utility Model Application Publication No. H5-28169, a bag width setting cam and an offset width adjustment cam are employed as a spacing adjustment mechanism for adjusting the spacing of the left and right grippers. The offset width is the distance that the clamping components of the grippers are moved, during the process of the table making its intermittent rotation, between the widest and narrowest spacing of the left and right grippers, and it is equal to one-half the difference between the maximum and minimum values for the spacing of the left and right grippers.
Japanese Patent No. 3,261,543 discloses a bag transfer device that is installed in a spout attachment and filling apparatus, and this bag transfer device comprises an intermittently rotating table and a plurality of pairs of left and right grippers disposed at a constant angular spacing around the table. In this spout attachment and filling apparatus, a method for manufacturing spouted bags (bags provided with spouts, and bags are filled with contents in this example) is executed in which flat bags, gusset bags, or the like that are square in top view are supplied to the left and right gripper pairs, and these bags are transferred intermittently along with the movement of the grippers while a corner at the upper end of each bag is cut off at an angle, spouts are attached to the cut corners of the bags, nozzles are inserted into the horizontal portions of the bag mouths, and then the bags are filled with a liquid through the nozzles. A spout that is thus attached to the angled corner of a square bag is called a corner spout, and this bag with a spout attached thereto is called a corner spouted bag.
Japanese Patent Application Laid-Open (Kokai) No. H7-187202 is similar to Japanese Patent No. 3,261,543 in that it also discloses a bag transfer device which is installed in a spout attachment and filling apparatus and comprises an intermittently rotating table and a plurality of pairs of left and right grippers disposed at a constant angular spacing around the table. In this spout attachment and filling apparatus, a method for manufacturing spouted bags (filled bags in this example) is executed in which bags are supplied to the left and right gripper pairs, and these bag are moved intermittently by the movement of the grippers while nozzles are inserted into the bag mouths and the bags are filled with a liquid, and then spouts are attached to the center parts of the horizontal bag mouths. A spout that is thus attached to the center part of a substantially horizontal mouth of a bag that is substantially square is called a center spout, and this bag is called a center spouted bag.
In the bag transfer device disclosed in Japanese Utility Model Application Publication No. H5-28169, the supply of bags to the grippers, the opening of the bag mouth, the filling of the bag with its contents, the sealing of the open part of the bag, the cooling of the sealed part of the bag, the removal of the sealed bag from the grippers, and other bag filling steps are carried out in order at various stop positions of the left and right grippers of the bag transfer device. A bag feed device, a bag opening device, a bag filling device, a bag sealing device, a bag cooling device, and so forth that perform the above steps are provided at various stop positions where the left and right grippers are stopped. All of the pairs of left and right grippers installed around the table are respectively disposed symmetrically with respect to a vertical plane that passes through the rotational center (axis) of the table, and these grippers are rotated intermittently along the movement path while this symmetrical layout is substantially maintained, with the spacing between them being increased or decreased as they are moved. The above-described vertical plane is called a reference plane in the present invention, and a layout state in which the left and right grippers are disposed symmetrically with respect to this reference plane is called a reference layout.
In such a bag filling and packaging apparatus as disclosed in Japanese Utility Model Application Publication No. H5-28169, generally, the various devices are installed at various stop positions, using the reference plane as a reference. More specifically, the bag feed device is, for example, installed so that the center line (a straight line that passes through the center in the bag width direction) of a bag supplied to the left and right grippers is located on the reference plane, the bag opening device is installed so that the pair of suction cups are moved back and forth on the reference plane, and the liquid filling device is installed so that a filling nozzle moves up and down on the reference plane.
In this bag filling and packaging apparatus, when a bag 1 (see FIG. 6A) that is open at the top and is rectangular in top view (as disclosed in Japanese Utility Model Application Publication No. H5-28169 and Japanese Patent Application Laid-Open (Kokai) No. H9-95318) is filled with a liquid, the center line CO of the bag 1 supplied by the bag feed device to the left and right grippers (only the clamping components 2 are shown) is located on a reference plane N. Then, when the grippers (clamping components 2) are stopped at the stop position where the opening step is performed, suction cups 3 are moved forward so as to come in contact with the surface of the bag 1 as indicated by two-dot chain lines in FIG. 6A, and this suction position is on the center line CO of the bag 1 (on the reference plane N). In the filling step as well, the filling nozzle are also moved up and down on the center line CO (on the reference plane N).
An example in which this bag filling and packaging apparatus is used so that a bag 4 shown in FIG. 6B, for example, instead of the bag 1, is filled with a liquid. The bag 4 is a corner spouted bag, and a spout 5 has been attached to the corner, which was cut at an angle. After being supplied by the bag feed device to the left and right grippers (the clamping components 2), the center line CO of the bag 4 is located on the reference plane N, but the center line C of the open part 6 at the top of the bag is offset from the reference plane (offset width G). When the grippers (the clamping components 2) are stopped at the stop position where the bag opening step is performed, the suction cups 3 are moved forward and come into contact with both surfaces of the bag 4 as indicated by the two-dot chain line in FIG. 6B, this suction position being on the center line CO of the bag 3 (on the reference plane N); and since the suction position is offset by the offset width G from the center line C of the open part 6, there is interference (difficulty) during the opening of the open part 6. Also, in the filling step, the filling nozzle are moved up and down on the center line CO (on the reference plane N), which is offset by the offset width G from the center line C of the open part 6, so that interference (difficulty) occurs during the insertion of the filling nozzle into the open part 6. In FIG. 6B, the height direction position of the bag 4 supplied to the grippers (the clamping components 2) and the height direction position of the suction cups 3 are adjusted depending on the bags 4.
If the horizontal position of the suction cups 3 is adjusted so that the suction cups 3 are moved onto the center line C of the open part 6, then there will be no interference (difficulty) during opening of the open part 6. Also, if the horizontal position of the filling nozzle is adjusted so that this filling nozzle are moved up and down on the center line C of the open part 6, then there will be also no interference (difficulty) during insertion of the nozzle into the open part 6 of the bag.
However, these adjustments of the horizontal position must be performed not only for the bag opening device and the bag filling device but also for any other subsequent (or downstream side) devices; and if the type of bag being processed changes to an ordinary flat bag from a spouted bag, it will be necessary to adjust back to the original reference plane N, and this can lead to a significant drop in the productivity of the bag filling and packaging apparatus.
One example of a bag filling and packaging apparatus that is for bags having spouts at corners such as these as described above is Japanese Patent Application Laid-Open (Kokai) No. 2009-220853.
In this spout attachment and filling apparatus disclosed in Japanese Patent No. 3,261,543, the supply of bags to the grippers, the corner cutting of the bag mouth, the opening of the bag mouth, the insertion of the spout into the bag mouth, the temporary sealing of the spout, the main sealing of the bag and spout, the cooling of the sealed part, the removal of the spouted bag from the grippers, and other such spout attachment steps are carried out in order at various stop positions of the left and right grippers of the bag transfer device. In the device of this Japanese Patent No. 3,261,543, filling with a liquid, sealing the open part, and so forth are carried out after the main sealing of the bag and spout is done; and in the description below in regards to this device, the steps after filling will not be considered (hereinafter the spout attachment and filling apparatus is referred to as a spout attachment device).
In this spout attachment device of Japanese Patent No. 3,261,543 as well, the layout of the left and right grippers of the bag transfer device is the reference layout described above. When, in this spout attachment device, a spout 8 (see FIG. 7A) is to be attached to the center of the open part 7 at the upper end of a bag 1 that is rectangular in the top view, the bag feed device, the opening device, the spout insertion and temporary sealing device, the spout main sealing device, the seal cooling device, and so forth that perform the above steps are installed at various stop positions so that the reference plane described above as a reference. More specifically, the bag feed device, for example, is installed so that the center line CO, which passes through the center in the width direction of the bag 1 supplied to the grippers 2 (the clamping components 2), is located in the reference plane N, the opening device is installed so that a pair of suction cups 3 are moved back and forth over the reference plane N, and the spout insertion and temporary sealing device is installed so that the spout 8 descends over the reference plane N and is inserted into the open part 7 of the bag 1.
A case will be considered below in which this spout attachment device is used to clamp the edges of the bag 9 shown in FIG. 7B, for example, with grippers (clamping components 2) so that a corner opening 11 that has been cut at an angle is horizontal, and a spout 8 is attached in the center of the corner opening 11. As seen from FIG. 7B, the horizontal position of the bag 9 supplied from the bag feed device to the grippers (the clamping components 2) is adjusted so that the clamping margin for the grippers (the clamping components 2) is substantially even on the left and right sides. In this case, first, in the opening step, the horizontal position of the suction cups 3 (on the reference plane N) deviates from the center line C of the corner opening 11 (with offset width H), and in the step of inserting and temporarily sealing the spout 8, the horizontal position of the spout 8 (on the reference plane N) deviates from the center line C of the corner opening 11 (offset width H). Accordingly, the spout 8 cannot be attached at the proper position.
If the horizontal position of the suction cups 3 is adjusted so that the suction cups 3 are moved onto the center line C of the corner opening 11, then there will be no interference (difficulty) during the opening of the corner opening 11. Also, if the horizontal position of the spout 8 is adjusted so that the insertion position of the spout 8 is on the center line C and the temporary sealing position is also on the center line C, then there will be no interference (difficulty) during the insertion of the spout 8 into the bag 9 or its temporary sealing.
However, this adjustment must be performed not only for the opening device and the spout insertion and temporary sealing device, but also for any other subsequent devices, and if the spouted bag to be processed changes from a corner spouted bag to a center spouted bag, then it will be necessary to adjust the above-described devices back to the original reference plane N, and this adjustment work can lead to a significant productivity drop of the spout attachment device. Furthermore, if a corner spouted bag is clamped by the grippers so that the corner opening is horizontal, then a difference in the angle at which the corner is cut will change the offset width H, so the above-described adjustment of the opening device, the spout attachment and temporary sealing device, and any subsequent devices will also need to be performed when the bag is changed to one with a different cut angle.